Endocrine Abstracts

Zebrafish has emerged as an important vertebrate in vivo model to study human disease. Steroidogenesis in zebrafish is not well characterised. Human CYP11A1 (hCYP11A1) catalyses the first step of steroidogenesis, the conversion of cholesterol to pregnenolone. Zebrafish Cyp11a1 (zCyp11a1) is essential during embryogenesis. Published data suggest that zCyp11a1 facilitates steroidogenesis in the interrenal (equivalent to mammalian adrenal), gonad and brain. We identified...

Introduction: The clinical features and complications of Cushing’s syndrome result from chronic excess of circulating cortisol, typically quantified by 24-h urinary free cortisol (UFC). LCI699 is a potent inhibitor of 11β-hydroxylase. Since 11β-hydroxylase catalyzes the final step of cortisol synthesis, LCI699 is a potential new treatment for all forms of Cushing’s syndrome.Methods: Adult patients with mild-to-severe Cushing’s di...

Background: Zebrafish is emerging as a comprehensive model system in endocrinology. Zebrafish synthesise steroid hormones in the interrenal (counterpart of the mammalian adrenal), gonad and brain. Data on steroidogenic pathways is patchy and steroidogenic enzymes in zebrafish have not been well characterised. Human 17α-hydroxylase (hCYP17A1) facilitates two conversion steps, 17α-hydroxylase and 17,20-lyase reactions in the adrenal and gonad. Two zCyp17a (zCyp17a1; zC...

Cytochrome P450 side-chain cleavage enzyme (CYP11A1) catalyses the first and rate-limiting step of steroidogenesis. CYP11A1 firstly converts cholesterol into 22R-hydroxycholesterol, which relies on mitochondrial steroidogenic acute regulatory protein (StAR)-mediated cholesterol import. Two further StAR-independent CYP11A1 reactions facilitate pregnenolone biosynthesis. CYP11A1 deficiency is rare and manifests with adrenal insufficiency (AI), and, in 46,XY individuals, with nor...

Mitotane (o,p’DDD) is the first-line treatment for metastatic adrenocortical carcinoma (ACC) and is also regularly used in the adjuvant setting after presumed complete removal of the primary tumour. Mitotane is considered an adrenolytic substance, but no information is available regarding distinct steroidogenic effects. Here we carried out steroid metabolomics by gas chromatography/mass spectrometry in 24-hour urine samples from 106 patients with ACC and with samples coll...

Congenital adrenal hyperplasia due to P450 oxidoreductase (POR) deficiency (ORD) results in disordered sex development (DSD) in individuals of both sexes. POR provides electrons to CYP17A1 thereby facilitating synthesis of the major androgen precursor dehydroepiandrosterone (DHEA). ORD disrupts this enzymatic step, resulting in deficient synthesis of 5α-dihydrotestosterone (DHT) via DHEA, readily explaining undervirilisation (46,XY DSD) in male ORD neonates. Female virili...

Cytochrome P450 side-chain cleavage enzyme (CYP11A1) catalyses the first and rate-limiting step of steroidogenesis, facilitating conversion of cholesterol to pregnenolone. Cholesterol, transported by steroidogenic acute regulatory protein (StAR) into the inner mitochondrial membrane, is converted by CYP11A1 into 22R-hydroxycholesterol. Subsequently, CYP11A1 converts 22R-hydroxycholesterol by 20alpha-hydroxylation and cleavage of the C20–C22 bond into pregnenolone. All pat...

Adrenal tumors have an incidence of 2–3% in the general population and the work-up of incidentally discovered adrenal masses represents a major burden to the health system. Differentiating adrenocortical adenoma (ACA) from adrenocortical carcinoma (ACC) represents a continuous challenge, with unfavorable sensitivities and specificities provided by tumor size, imaging and even histology. Here, we aimed to develop a reliable screening tool for the detection of adrenal malig...

Background: Glucocorticoids play a key role in determining body fat distribution. Excess circulating glucocorticoids lead to intrahepatic fat accumulation. Obesity is associated with enhanced glucocorticoid production but this is offset by enhanced degradation such that circulating steroid concentrations are normal. However, tissue-specific pathways may lead to different degrees of cortisol exposure in different organs. Local steroid exposure in the liver is determined by the ...

CYP17A1 is a key enzyme of human steroidogenesis, which is unique in that it catalyses two reactions, 17-hydroxylase activity converting pregnenolone and progesterone to 17-hydroxypregnenolone (17Preg) and 17-hydroxy-progesterone, respectively, and 17,20 lyase activity, responsible for the conversion of 17Preg to dehydroepiandrosterone the crucial precursor of human sex steroid biosynthesis. 17-hydroxylase deficiency, a variant of congenital adrenal hyperplasia, results in glu...